A person that was given birth to, under a normal environment, but later in life they decided to be an unintelligent person, by voluntarily saying something embarrassing or voluntarily doing something embarrassing in public.

The top filing cabinet is opened by an office worker, due to him or her is getting some files(of course), then doesn't close the top filing cabinet and starts to open the bottom filing cabinet to get another thing to get another file. Then the office worker closes the bottom after a finished search at the bottom cabinet, and knowing that the top cabinet is still opened, decides to get up and "involuntarily" banging his or her head on the bottom of the top filing cabinet drawer is a dee dee dee.